Water-dilutable polyesters with cyclic imide and isocyanurate structure

ABSTRACT

The present invention relates to novel polyesterpolyols with cyclic imide and isocyanurate structure and to their use in coating compositions.

The present invention relates to novel water-dilutable polyesterpolyolswith cyclic imide and isocyanurate structure and to their use in coatingcompositions.

From the prior art it is known that polyisocyanates containing freeisocyanate groups and having certain selected properties, such as, forexample, viscosity or hydrophilicity, can be used in combination withdifferent hydroxy-functional binders, examples being polyesters,polyacrylates or polyurethanes, in aqueous medium as crosslinkers undervarious conditions. Such systems are known, for example, from EP-A 0 358979, EP-A 0 469 389, EP-A 0 496 205, EP-A 0 537 568, EP-A 0 583 728,EP-A 0 654 053 and DE-A 41 35 571.

Also known from the prior art are aqueous clearcoat materials based onspecial acrylate dispersions and amino resins, in combination whereappropriate with blocked polyisocyanates. Examples thereof are disclosedin EP-A 0 365 775, EP-A 0 363 723, EP-A 0 521 926 and EP-A 0 521 927.The coating materials recited therein are unsuitable, however, for lowbaking temperatures. In particular, they cannot be processed on partsmade of plastic.

DE-A 195 38 061 describes water-dilutable polyesters with narrowcompositional relationships, comprising both aromatic and cycloaliphaticbuilding blocks containing acid groups. The polyesters described areused preferably in automotive clearcoat materials for automotive OEMfinishing. A disadvantage with these polyesters is the inadequateresistance to hydrolysis.

DE-A 42 26 242 describes two-component polyurethane coating materialscomprising, as hydroxy-functional polymer, water-dilutablepolyesterpolyols in which trishydroxyethyl isocyanurate is used as apolyol building block.

Polymers with cyclic imide structures, e.g. polyamideimides fromdiamines and/or diisocyanates, tricarboxylic anhydrides andε-caprolactam, are frequently used for heat-resistant coatings in wireenamelling, as disclosed in DE-A 38 17 614 or DE-A 33 32 031. Alsodescribed are combinations with modified polyesters, for example in DE-A32 13 257. These polymers, however, are not water-dilutable.

The object of the present invention was to provide novel polyesterssuitable for preparing hydrolysis-resistant polyester dispersions orpolyester solutions which are aqueous or can be diluted in water. Thepolyester dispersions ought additionally to be able to be used forpreparing high-grade aqueous two-component polyurethane coatingmaterials and ought to meet the requirements imposed on the propertiesof the coating, for example drying, surface quality such as hardness,gloss, levelling, smoothness, fullness and effect, polishability andresistance to water, chemical agents or atmospheric effects, weatheringand mechanical influences. Moreover, the polyesters of the inventionought also to possess an elasticity such that they are suitable forcoating substrates made of plastic.

This object has been achieved through the provision of polyesters withcyclic imide and isocyanurate structure.

The invention accordingly provides polyesterpolyols

-   -   which comprise structural units of the general formula (I)

in which

-   R¹, R² and R³ independently of one another are identical or    different and stand for organic, optionally heteroatom-containing    radicals which comprise one or more of the following structural    units:

-   -   and which comprise structural units of the general formula (II)

-   -   and/or which comprise structural units of the general formula        (III)

Likewise provided by the present invention are polyesterpolyols

-   -   which comprise structural units of the general formula (I)

in which

-   R¹, R² and R³ independently of one another are identical or    different and stand for organic, optionally heteroatom-containing    radicals which comprise one or more of the following structural    units:

and which, as end groups,

-   -   comprise structural units of the general formula (IV)

-   -   and/or structural units the general formula (V)

in which

-   R⁴ and R⁵ independently of one another are identical or different    and    -   stand for hydrogen, halogen, optionally substituted C₁–C₁₈        alkyl, C₂–C₁₈ alkenyl, C₂–C₁₈ alkynyl, C₃–C₁₂ cycloalkyl, C₃–C₁₂        heterocycloalkyl, C₆–C₂₄ aryl, C₆–C₂₄ heteroaryl, C₁–C₁₈ alkoxy,        C₁–C₁₈ alkylthio or C₁–C₁₈ alkylamino radicals or    -   with the joining carbon atom of the C₄N five-membered ring form        a C₃–C₁₂ cycloalkyl or C₂–C₁₃ heterocycloalkyl radical which        optionally contains oxygen, nitrogen and/or sulphur or    -   both together with the joining carbon atoms of the C₄N        five-membered ring form a fused cyclic or polycyclic ring system        which is saturated, unsaturated, partly or fully aromatic, is        optionally substituted and optionally contains oxygen, nitrogen        and/or sulphur.

The polyesterpolyols of the invention contain free hydroxyl and carboxylgroups.

The polyesterpolyols of the invention have hydroxyl numbers from 10 to400 mg KOH/g, preferably from 15 to 350 mg KOH/g and more preferablyfrom 20 to 300 mg KOH/g, and acid numbers of from 5 to 100 mg KOH/g,preferably from 10 to 80 mg KOH/g and more preferably from 20 to 60 mgKOH/g.

Suitable synthesis components for the polyesters of the invention areacid components (A), cyclic lactams (B), alcohol components (C) andisocyanurate components (D).

Examples of suitable acid components are difunctional carboxylic acidsor their derivatives (A1) such as aliphatic, cycloaliphatic or aromaticdifunctional carboxylic acids or their anhydrides. Aliphaticdifunctional carboxylic acids are, for example, aliphatic saturateddicarboxylic acids such as oxalic acid, malonic acid, dimethylmalonicacid, succinic acid, adipic acid, glutaric acid, azelaic acid, pimelicacid, suberic acid, sebacic acid or the possible anhydrides of theseacids and also unsaturated dicarboxylic acids such as fumaric acid,maleic acid, itaconic acid, citric acid or the possible anhydrides ofthese acids, for example. Preference is given to adipic acid and maleicanhydride. Cycloaliphatic difunctional carboxylic acids are, forexample, cyclopentanedicarboxylic acid, 1,3-,1,4-cyclohexanedicarboxylic acid, 2,5-norbornenedicarboxylic acid,endoethylenecyclohexanedicarboxylic acid and methyltetrahydrophthalicacid, tetrahydrophthalic acid, hexahydrophthalic acid or the possibleanhydrides of these acids. Preference is given to1,4-cyclohexane-dicarboxylic acid, tetrahydrophthalic anhydride andhexahydrophthalic anhydride. Examples of suitable aromatic difunctionalcarboxylic acids are terephthalic acid, isophthalic acid, phthalic acid,naphthalenedicarboxylic acid, biphenyldicarboxylic acid or the possibleanhydrides of these acids. It is likewise possible to use mixtures ofthese acids as component (A1). Preference is given to phthalicanhydride, isophthalic acid and terephthalic acid.

Likewise suitable as acid component are carboxylic acids having afunctionality of more than 2 (A2), such as trimellitic acid or trimesicacid (functionality=3, (A2′)) or pyromellitic acid orbenzophenonetetracarboxylic acid (functionality=4, (A2″)) or thepossible anhydrides of these acids. It is likewise possible to usemixtures of these acids as component (A2).

Suitable monocarboxylic acids (A3) are selected from the group of thealiphatic, cycloaliphatic or aromatic, saturated or unsaturated,monocarboxylic acid having 1 to 18 carbon atoms, preferably 1 to 12 andmore preferably 1 to 8 carbon atoms, such as formic acid, acetic acid,propionic acid, butyric acid, isobutyric acid, valeric acid,2-methylbutanoic acid, 3-methylbutanoic acid, 2,2-dimethylpropanoicacid, 2-ethylbutanoic acid, 2-ethylhexanoic acid, octanoic acid,decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid,octadecanoic acid, saturated and unsaturated fatty acids,cyclohexanecarboxylic acid, cyclohexenoic acid, phenylacetic acid andbenzoic acid or the anhydrides of these acids. It is likewise possibleto use mixtures of these acids as component (A3). Preference is given to2-ethylhexanoic acid, saturated and/or unsaturated fatty acids,cyclohexanoic acid and benzoic acid.

Cyclic lactams (B) are compounds of the general formula (VI)

where

-   n stands for an integer from 3 to 5.

Examples of suitable compounds of component (B) are γ-butyrolactam andε-caprolactam, preference being given to ε-caprolactam.

Suitable alcohol components (C) include the following:

-   (C1) aliphatic or cycloaliphatic C₃–C₁₀ polyols having a    functionality of more than 2,-   (C2) aliphatic or cycloaliphatic C₂–C₁₈ diols,-   (C3) aliphatic, cycloaliphatic or araliphatic monofunctional C₁–C₁₈    alcohols.

Component (C1) comprises aliphatic or cycloaliphatic C₃–C₁₀ polyolshaving a functionality of more than 2, such as glycerol,trimethylolethane, trimethylolpropane, pentaerythritol,dipentaerythritol, sorbitol, reaction products of these polyols withε-caprolactone or alkylene oxides. Preference is given to C₃–C₈ polyols,such as glycerol, trimethylolpropane and pentaerythritol. It is alsopossible to use mixtures of the said polyols as component (C₁).

Component (C2) comprises aliphatic or cycloaliphatic C₂–C₁₈ diols,alcohols optionally containing ether oxygen atoms, such as ethyleneglycol, diethylene glycol, triethylene glycol, neopentylglycol,propane-1,2-diol and 1,3-diol, dipropylene glycol, butane-1,2-diol,-1,3-diol, -2,3-diol and -1,4-diol, pentane-1,5-diol,2,2-diethylpropanediol, hexane-1,6-diol and -2,5-diol,2-methyl-2,4-pentanediol, 2-methyl-1,3-propanediol,2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol,2-methyl-2-propyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol,cyclohexane-1,4-dimethanol, cyclohexane-1,2-, -1,3- and -1,4-diol,2,2-bis(4-hydroxycyclohexyl)propane andoctahydro-4,7-methano-1H-indenedimethanol or reaction products of thesediols with ε-caprolactone or alkylene oxides. Preference is given tousing C₂–C₁₂ diols. Mixtures of such diols can likewise be used ascomponent (C2). Preference is given to ethylene glycol, diethyleneglycol, propane-1,2-diol, neopentylglycol, hexane-1,6-diol andcyclohexane-1,4-dimethanol.

Suitable compounds for component (C3) are aliphatic, cycloaliphatic oraraliphatic monofunctional C₁–C₁₈ alcohols, such as methanol, ethanol,1- and 2-propanol, 1-and 2-butanol, isobutanol, tert-butanol, 1-, 2- and3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol,2,2-dimethylpropanol, 1-, 2- and 3-hexanol, 4-methyl-2-pentanol,2-ethyl-1-butanol, 2,2-dimethylpropanol, 1-octanol, 2-ethyl-1-hexanol,1-nonanol, trimethyl-1-hexanol, 1-decanol, 1-dodecanol, 1-tetradecanol,1-hexadecanol, 1-octadecanol, cyclohexanol, 2-, 3- and4-methyl-cyclohexanol, hydroxymethylcyclohexane,3,3,5-trimethylcyclohexanol, 4-tert-butylcyclohexanol, benzyl alcohol,1-methyl-4t-isopropylcyclohexanol=(−)-menthol, decahydro-2-naphthol,(1R-endo)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol,(1R-exo)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol and(1R)-6,6-dimethylbicyclo[3.1.1]hept-2-ene-2-methanol or reactionproducts of these monoalcohols with ε-caprolactone or alkylene oxides.Preference is given to C₁–C₁₂ alcohols, such as 1- and 2-butanol,isobutanol, 2-ethyl-1-hexanol, 1-nonanol, 1-decanol, 1-dodecanol,cyclohexanol, 3,3,5, -trimethylcyclohexanol, 4-tert-butylcyclohexanol,benzyl alcohol. Particular preference is given to C₁–C₁₀ alcohols, suchas 2-ethyl-1-hexanol, cyclohexanol, 3,3,5,-trimethylcyclohexanol,4-tert-butylcyclohexanol and benzyl alcohol. Mixtures of suchmonoalcohols can likewise be used as component (C3).

Suitable as isocyanurate component (D) are trishydroxyethyl isocyanate(D1) or the reaction products with ε-caprolactone or alkylene oxides.

Likewise suitable as isocyanurate component (D) areisocyanurate-group-containing modification products of simplediisocyanates (D2), such as hexamethylene diisocyanate (HDI),1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophoronediisocyanate, IPDI), diisocyanatodicyclohexylnethane, 2,4- and2,6-diisocyanatotoluene (TDI), 2,4′- and4,4′-diisocyanatodiphenylmethane. It is preferred to use (D1).

The invention likewise provides a process for preparing thepolyesterpolyols of the invention comprising structural units of thegeneral formula (I) and (II) and/or (III) by

-   (I) reacting an anhydride of trimellitic acid and/or of pyromellitic    acid with a cyclic lactam (B),-   (II) synthesizing a hydroxy-functional polyester by adding    -   trishydroxyethyl isocyanurate (D1) and    -   optionally an alcohol component (C) containing    -   one or more aliphatic or cycloaliphatic C₃–C₁₀ polyols having a        functionality of more than 2 (C1),    -   one or more aliphatic or cycloaliphatic C₂–C₁₈ diols (C2) and    -   one or more aliphatic, cycloaliphatic or araliphatic        monofunctional C₁–C₁₈ alcohols (C3),    -   and also optionally adding an acid component (A) comprising        -   one or more difunctional carboxylic acids or their            anhydrides (A1) and/or        -   one or more polyfunctional carboxylic acids or their            anhydrides (A2) and        -   one or more monocarboxylic acids (A3),    -   and also optionally adding an isocyanurate-containing isocyanate        component (D2).

The invention likewise provides a process for preparing thepolyesterpolyols of the invention comprising structural units of thegeneral formula (I) and (IV) and/or (V) by

-   (I) reacting an anhydride of a difunctional carboxylic acids (A1)    with a cyclic lactam (B),-   (II) synthesizing a hydroxy-functional polyester by adding    -   trishydroxyethyl isocyanurate (D1) and    -   optionally an alcohol component (C) containing    -   one or more aliphatic or cycloaliphatic C₃–C₁₀polyols having a        functionality of more than 2 (C1),    -   one or more aliphatic or cycloaliphatic C₂–C₁₈ diols (C2) and    -   one or more aliphatic, cycloaliphatic or araliphatic        monofunctional C₁–C₁₈ alcohols (C3),    -   and also optionally by adding an acid component (A) comprising        -   one or more difunctional carboxylic acids or their            anhydrides (A1) and/or        -   one or more polyfunctional carboxylic acids or their            anhydrides (A2) and        -   one or more monocarboxylic acids (A3),    -   and also optionally by adding an isocyanurate-containing        isocyanate component (D2).

A general overview of the (preparative) preparation of polyesterpolyolsand of the reaction conditions is given for example in “UllmannsEncyclopädie der Technischen Chemie”, Verlag Chemie Weinheim, 4thedition (1980) volume 19, pages 61 ff, or by H. Wagner and H. F. Sarx in“Lackkunstharze”, Carl Hanser Verlag, Munich (1971), pages 86 to 152.

The polyesterpolyols of the invention can be processed both tosolvent-containing binders or solutions and to aqueous binders oraqueous solutions or dispersions. To prepare aqueous dispersions of thepolyesters of the invention the free carboxyl groups are neutralizedwith a neutralizing agent.

It is likewise possible in the process of the invention to introduce thestructural units (I) exclusively by way of the components (D2).

In one preferred embodiment of the process of the invention acidanhydride and lactam, optionally in the presence of alcohols (C)selected from group (C1) to (C3) and component (D1), are reacted withone another in a first stage, giving structural units containing cyclicimide groups. In this case it is preferred to use (C2) as alcoholcomponents. This is followed in a second stage by the esterificationwith the remaining polyester building blocks, such as acid components(A) and alcohol components (C). As acid component it is preferred to useacid component (A1). The isocyanurate structures (I) are introduced intothe polyesterpolyols of the invention preferably by component (D1). Theprocess of the invention is preferably conducted in the melt, optionallyin the presence of a catalytic amount of a usual esterificationcatalyst, such as acids, bases or transition metal compounds, forexample, such as titanium tetrabutoxide, dibutyltin oxide orbutylstannic acid, for example, at temperatures from 80 to 270° C.,preferably from 100 to 260° C. Optionally it is also possible to add anazeotrope former, such as xylene, to discharge the water of reaction.The esterification reaction is carried out until the target values forthe hydroxyl number and acid number and also for the viscosity have beenreached. Alternatively it is possible to introduce the isocyanuratestructures (I) as well into the isocyanurate-containing isocyanatecomponent (D2) by reacting the polyesterpolyol. Preferably, in a thirdstage, the hydroxy-functional polyester is reacted with a cycliccarboxylic anhydride selected from the group of the difunctionalcarboxylic acids (A1) and/or trifunctional carboxylic acids (A2′), withring opening and half-ester formation.

It is likewise possible in principle to react all of the components inone step to give the polyesters of the invention.

The carboxyl groups formed in the polyesterpolyols of the invention mayoptionally be neutralized with a neutralizing agent, completely,partially or over-neutralized, so that the polyester according to theinvention becomes water-dilutable. In that case the neutralizing agentcan be added before, during or after the ester of the invention istransferred to the aqueous phase.

The invention further provides aqueous solutions or dispersionscomprising the polyesterpolyols of the invention.

To prepare such polyester solutions or dispersions either thepolyesterpolyol of the invention, where appropriate with strongshearing, such as vigorous stirring, for example, is introduced intowater or, conversely, water is stirred into the polyesterpolyol. Thedispersing or solution medium may at the same time contain theneutralizing agent and/or other additives as well.

Suitable neutralizing agents (E) include not only inorganic but alsoorganic bases. Preference is given to using primary, secondary andtertiary amines, such as ammonia, ethylamine, propylamine,dimethylamine, dibutylamine, cyclohexylamine, benzylamine, morpholine,piperidine, diethanolamine and triethanolamine. It is preferred to usetertiary amines, such as triethylamine, N,N-dimethylethanolamine,N,N-diethylethanolamine, triethanolamine, triisopropylamine,N-methylmorpholine, 2-amino-2-methylpropanol. Particular preference isgiven to N,N-dimethylethanol-amine, triethanolamine and triethylamine.

The neutralizing agents (E) are normally used in amounts of from 0.4 to1.3 mol, preferably from 0.5 to 1.2 mol and more preferably from 0.6 to1.1 mol, relative to each mole of free carboxyl groups in the polyester.

It is also possible to dissolve the polyesterpolyols of the invention inan organic solvent after the second or third reaction stage and to usethe polyester solution for preparing solvent-containing binder.

Organic solutions of the polyesterpolyols of the invention are thereforefurther provided by the invention.

Examples of suitable solvents are esters, such as ethyl acetate, butylacetate, methoxypropyl acetate, methylglycol acetate, ethylglycolacetate, diethylene glycol monomethyl ether acetate; ketones, such asmethyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone;aromatics, such as toluene and xylene, and also the relativelyhigh-boiling hydrocarbon mixtures that are common in paint chemistry.

From the polyesterpolyols of the invention and/or from their aqueousdispersions or aqueous or organic solutions it is possible to preparebinders for two-component (2K) polyurethane coating materials.

In the case of blocked polyisocyanates it is likewise possible to usethe polyester-polyols of the invention or their solutions or dispersionsin one-component (1K) polyurethane coating materials. It is likewisepossible to use the polyesterpolyols of the invention in combinationwith amino resins, e.g. melamine resins, in one-component (1K) coatingmaterials. Preference is given to their use as 2K polyurethane coatingmaterials.

Likewise provided by the invention are coating compositions comprisingthe polyesterpolyols of the invention.

As polyisocyanate component it is possible to use non-blocked or blockedpoly-isocyanates which are obtainable by modifying simple aliphatic,cycloaliphatic, araliphatic and/or aromatic diisocyanates,polyisocyanates synthesized from at least two diisocyanates and having auretdione, isocyanurate, allophanate, biuret, imino-oxadiazinedioneand/or oxadiazinetrione structure, as described exemplarily for examplein J. Prakt. Chem. 336 (1994) page 185–200.

Suitable diisocyanates for preparing the polyisocyanates arediisocyanates which are obtainable by phosgenation or by phosgene-freeprocesses, for example by thermal urethane cleavage, and which come fromthe molecular weight range from 140 to 400 and contain aliphatically,cycloaliphatically, araliphatically and/or aromatically attachedisocyanate groups, such as, for example, 1,4-diisocyanatobutane,1,6-diisocyanatohexane (HDI), 2-methyl-1,5-diisocyanatopentane,1,5-diisocyanato-2,2-dimethylpentane, 2,2,4- and/or2,4,4-trimethyl-1,6-diisocyanatohexane, 1,10-diisocyanatodecane, 1,3-and 1,4-diisocyanatocyclohexane, 1,3- and1,4-bis(iso-cyanatomethyl)cyclohexane,1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophoronediisocyanate, IPDI), 4,4′-diisocyanatodicyclohexylmethane,1-isocyanato-1-methyl-4(3)-isocyanatomethylcyclohexane,bis(isocyanatomethyl)-norbornane, 1,3- and1,4-bis(2-isocyanatoprop-2-yl)benzene (TMXDI), 2,4- and2,6-diisocyanatotoluene (TDI), 2,4′- and4,4′-diisocyanatodiphenylmethane, 1,5-diisocyanatonaphthalene or anydesired mixtures of such diisocyanates.

Moreover, triisocyanates such as triphenylmethane 4,4′,4″-triisocyanateand/or 4-isocyanatomethyloctane 1,8-diisocyanate are also suitable.

It is preferred to use polyisocyanates or polyisocyanate mixtures of thetype mentioned containing exclusively aliphatically and/orcycloaliphatically attached isocyanate groups.

Particularly preferred polyisocyanates or polyisocyanate mixtures arethose with isocyanurate and/or biuret structure based on HDI, IPDIand/or 4,4′-diisocyanato-dicyclohexylmethane.

In order to achieve better incorporability of the said polyisocyanatesinto aqueous binders, the polyisocyanates are preferably hydrophilicallymodified. Use is made for this purpose, by methods which are known perse, of polyisocyanates of the abovementioned type. Thehydrophilicization can take place, for example, anionically,cationically or nonionically, by way of internal or externalemulsifiers.

Polyisocyanates hydrophilicized by internal emulsifiers are, forexample, those which have been hydrophilicized by carboxyl groups andwhich, following neutralization of the carboxyl groups, can be stirredwith very fine division into aqueous systems without the need for highshearing forces. Such polyisocyanates are, for example, subject-matterof EP-A 443 138 and EP-A 510 438. It is additionally possible to usepolyisocyanates hydrophilically modified by polyethers. The preparationof such water-dispersible polyisocyanates containing urethane groups is,for example, subject-matter of EP-A 206 059, EP-A 540 985 and of U.S.Pat. No. 5,200,489. Water-dispersible polyisocyanates which containallophanate groups and have been hydrophilically modified withpolyethers, and their preparation, are subject-matter of EP-A 0 959 087.2K PU coating materials based on these polyisocyanates aresubject-matter of EP-A 959 115 and of EP-A 1 065 228.

Likewise suitable are the water-emulsifiable polyisocyanates describedin EP-A 0 703 255, comprising as ionic emulsifiers reaction products ofpolyisocyanates and any desired hydroxy-, mercapto- or amino-functionalcompounds having at least one sulphur-acidic group or anion thereof.Preferred sulphur-acidic synthesis components specified there forpreparing the emulsifiers are hydroxysulphonic acids containingaliphatically attached OH groups or the salts of such hydroxysulphonicacids, examples being special polyethersulphonates, as traded, forexample, under the name Tegomer® (Th. Goldschmidt AG, Essen, Del.),bisulphite adducts with unsaturated alcohols, hydroxyethanesulphonic andhydroxypropanesulphonic acid, and amino-sulphobetaines preparable byquaternizing tertiary amino alcohols with 1,3-propane sultone. Alsopreferred are 2-(cyclohexylamino)ethanesulphonic acid and3-(cyclo-hexylamino)propanesulphonic acid or salts thereof ashydrophilicizing components.

Examples of suitable external emulsifiers are anionic emulsifiers, suchas those based on alkyl sulphate, alkylarylsulphonates, alkylphenolpolyether sulphates as indicated for example in Houben-Weyl, Methodender organischen Chemie, additional and supplementary volumes, 4^(th)Edition, Volume E20, 1987 (Part 1, pages 259 to 262) or alkyl polyethersulphates, or nonionic emulsifiers, such as the alkoxylation products,preferably ethoxylation products, of alkanols, phenols or fatty acids.

The polyisocyanates have an NCO content of 1 to 45% by weight,preferably from 8 to 25% by weight. They may optionally be diluted witha solvent which is at least partly miscible with water but is inerttowards isocyanate groups.

Preference is given to using polyisocyanates which contain urethanegroups and are hydrophilicized by internal emulsifiers, which aresubject-matter of EP-A 540 985, for example, and polyisocyanatescontaining allophanate groups, which are described, for example, in EP-A0 959 087. Particular preference is given to using polyether-modifiedpolyisocyanates containing allophanate groups, disclosed in EP-A 0 959087. Preferably 60 to 99 mol % of the polyether are attached to thepolyisocyanate by way of allophanate groups.

The present invention also provides a process for preparingsolvent-containing or aqueous coating compositions, characterized inthat the polyisocyanate component and optionally further binders areincorporated by stirring or emulsification into the binder comprisingthe polyesterpolyols of the invention.

The quantitative ratio of binder component and curing component in thiscase is chosen such that for each hydroxyl group of the resin componentthere are from 0.1 to 3.0, preferably from 0.5 to 2.0 and morepreferably from 0.7 to 1.7 isocyanate groups of the curing component.

Prior to the addition of the curing component it is possible toincorporate the customary auxiliaries and additives of coatingstechnology into the binder component or the curing component, butpreferably the binder component. These include, for example, defoamers,thickeners, levelling agents, pigments, fillers, emulsifiers, dispersingassistants, light stabilizers and also solvents.

The desired processing viscosity is set in general by adding solvent orwater. In order to set specific processing viscosities or to obtainparticular rheological properties it is also possible to use thickenersor combinations of different thickeners, such as ionic and associativethickeners.

Examples of suitable substrates are mineral building material surfaces,road coverings, wood and wood-based materials, metallic surfaces,plastics, glass, textiles, fabric or paper.

The coating materials comprising the polyesterpolyols of the inventionare used as one-component (1K) or as two-component (2K) coatingmaterials.

The coating materials comprising the polyesterpolyols of the inventionare used preferably as primers, surfacers, pigmented topcoat materialsand clearcoat materials in the field of automotive refinish andlarge-vehicle finishing, in general industrial coating, in the coatingof plastics, in wood coating, and also in corrosion controlapplications. Particular preference is given to use for applicationswhich call for particularly high application safety, rapid drying, arapid increase in hardness to a high ultimate hardness but with goodelasticity, very good optical properties, characterized by very goodlevelling and high gloss, and also good resistance to solvents,chemicals, water and weathering, such as, for example, in automotiverefinish and large-vehicle finishing or in general industrial coating.

The coating compositions comprising the polyesterpolyols of theinvention can be applied to the respective substrates by any of a verywide variety of spraying techniques, such as air-pressure spraying,airless spraying or electrostatic spraying techniques, usingone-component or two-component spraying units, or else by brushing,rolling, flowcoating or knifecoating.

The coatings are dried and cured in general under normal temperatureconditions, i.e. without heating of the coating. However, it is alsopossible to use the coating compositions of the invention to producecoatings which following application are dried and cured at elevatedtemperature, e.g. at 40 to 250° C., preferably at 40 to 150° C. and morepreferably at 40 to 100° C.

The polyesterpolyols of the invention with cyclic imide groups andisocyanurate groups lead to improved properties in the coatings producedfrom them. Solvent-containing and aqueous two-component polyurethanecoating materials comprising the polyesterpolyols of the invention givecoatings featuring very rapid drying, high hardness coupled with goodelasticity, high resistance to solvents, chemicals and water, very goodlevelling, and also very high gloss. Aqueous dispersions based on thepolyesterpolyols of the invention feature better storage stability thanthe polyester dispersions of the prior art, even at elevatedtemperatures of 40 to 50° C., and a better hydrolysis resistance.

EXAMPLES

In the examples below all percentages are by weight.

The stated “solids content” was determined by the thick-layer method, inwhich a defined amount of sample is dried in a convection oven at 125°C. for 1 h and the solids content is calculated from the resultantdecrease in weight (based on DIN EN ISO 3251).

The acid number (mg KOH/g sample) was determined by titration with 0.1mol/l NaOH solution on the basis of DIN 53 402.

The OH number (mg KOH/g sample) was determined by acetylation,hydrolysis and subsequent titration of the liberated HCl with 0.1 mol/lNaOH on the basis of DIN 53 240.

Unless otherwise specified the viscosities were determined at 23° C. ona VT 550 rotational viscometer from Haake GmbH, Karlsruhe, DE.

The indication “as-supplied form” refers to the as-is solution ordispersion of the polyesterpolyols; by “resin solids” are meant thenonvolatile resin fraction of the solution or dispersion present.

Example 1

Preparation of a Water-dilutable Polyesterpolyol I

335 g of neopentylglycol, 636 g of 1,4-cyclohexanedimethanol, 734 g oftrimellitic anhydride and 432 g of ε-caprolactam were weighed outtogether into a reactor equipped with stirrer, heating, automatictemperature control, nitrogen inlet, column, water separator andreceiver and, with stirring and passing of nitrogen through the system,were heated to 230° C. in such a way that the overhead temperature ofthe column did not exceed 103° C. During this procedure the water ofreaction was separated off. Condensation was carried out to an acidnumber of ≦5 mg KOH/g. The system was then cooled to 150° C. and 829 gof neopentylglycol, 394 g of trimethylolpropane, 627 g oftrishydroxyethyl isocyanurate and 1787 g of phthalic anhydride wereadded. Subsequently, with stirring and passing of nitrogen through thesystem, the reaction mixture was heated to 220° C. in such a way thatthe overhead temperature of the column did not exceed 103° C. Duringthis procedure, water of reaction continued to separate out. After theend of distillation, the water separator was replaced by a distillationbridge and the reaction mixture was stirred at 220° C. until theoverhead temperature of the column fell to below 90° C. The column wasremoved and the reaction mixture was condensed with an increasednitrogen flow to an acid number of ≦5 mg KOH/g. The system was thencooled to 140° C., 418 g of trimellitic anhydride were added and themixture was stirred at 170° C. until an acid number of 35 mg KOH/g wasreached. Up to this point in the preparation of the polyester a total of1770 g of polyester resin had been removed as a result of sampling andother removals. The remaining mixture was then cooled to 130° C., and210 g of dipropylene glycol dimethyl ether were added and dissolved inat 100° C. over one hour. The resulting solution was then run off into amixture of 104 g of N,N-dimethylethanolamine and 2805 g of deionizedwater, which was at 50° C., and the solution was stirred into themixture at 50° C. over the course of one hour. The resulting product wasadjusted with further water to a solids content of 53% by weight. Thisgave an opaque dispersion with a bluish shimmer which had a solidscontent of 52.0% by weight in terms of polyesterpolyol, an acid numberof 16.9 mg KOH/g (based on as-supplied form), an OH number of 104 mgKOH/g (based on resin solids) and a viscosity of 1498 mPa·s at 23° C.The dispersion contained 2.8% by weight of dipropylene glycol dimethylether, 1.5% by weight of N,N-dimethylethanolamine and 42.7% by weight ofwater. The product can be diluted further with water and was suitablefor use in aqueous two-component polyurethane coating materials.

Example 2

Preparation of a Water-dilutable Polyesterpolyol II

In analogy to example 1 a water-dilutable polyesterpolyol or an aqueouspolyester was prepared from the following components:

1523 g of trimethylolpropane, 552 g of trishydroxyethyl isocyanurate,874 g of trimellitic anhydride, 515 g of ε-caprolactam, 725 g of2-ethylhexanoic acid, 446 g of benzoic acid, 808 g of hexahydrophthalicanhydride, 347 g of trimellitic anhydride, 210 g of N-methylpyrrolidoneand 120 g of N,N-dimethylethanolamine. The resulting product wasadjusted with water to a solids content of 43% by weight. This gave anopaque dispersion with a bluish shimmer which had a solids content of42.6% by weight in terms of polyesterpolyol, an acid number of 18.3 mgKOH/g (based on as-supplied form), an OH number of 84 mg KOH/g (based onresin solids) and a viscosity of 2253 mPa·s at 23° C. The dispersioncontained 2.2% by weight of N-methylpyrrolidone, 1.4% by weight ofN,N-dimethylethanolamine and 53.4% by weight of water. The product canbe diluted further with water and is suitable for use in aqueoustwo-component polyurethane coating materials.

Example 3

Preparation of a Water-dilutable Polyesterpolyol III

In analogy to example 1 a water-dilutable polyesterpolyol or an aqueouspolyester was prepared from the following components:

1215 g of trishydroxyethyl isocyanurate, 770 g of trimellitic anhydride,454 g of ε-caprolactam, 1006 g of trimethylolpropane, 725 g of2-ethylhexanoic acid, 446 g of benzoic acid, 727 g of hexahydrophthalicanhydride, 347 g of trimellitic anhydride, 210 g of N-methylpyrrolidoneand 121 g of N,N-dimethylethanolamine. The resulting product wasadjusted with water to a solids content of 49% by weight. This gave anopaque dispersion with a bluish shimmer which had a solids content of48.1% by weight in terms of polyesterpolyol, an acid number of 19.1 mgKOH/g (based on as-supplied form), an OH number of 78 mg KOH/g (based onresin solids) and a viscosity of 2830 mPa·s at 23° C. The dispersioncontained 2.6% by weight of N-methylpyrrolidone, 1.6% by weight ofN,N-dimethylethanolamine and 46.8% by weight of water. The product canbe diluted further with water and is suitable for use in aqueoustwo-component polyurethane coating materials.

Example 4, Comparative

Preparation of a Water-dilutable Polyesterpolyol IV

Polyesterpolyol prepared in analogy to example 1, but trimelliticanhydride and ε-caprolactam have been replaced by isophthalic acid andtrishydroxyethyl isocyanurate by trimethylolpropane.

In analogy to example 1 a water-dilutable polyesterpolyol or an aqueouspolyester was prepared from the following components:

1286 g of neopentyl glycol, 574 g of 1,4-cyclohexanedimethanol, 846 g oftrimethylolpropane, 586 g of isophthalic acid, 2089 g of phthalicanhydride, 418 g of trimellitic anhydride, 210 g of dipropylene glycoldimethyl ether and 123 g of N,N-dimethylethanolamine. The resultingproduct was adjusted with water to a solids content of 41% by weight.This gave an opaque dispersion with a bluish shimmer which had a solidscontent of 40.5% by weight in terms of polyesterpolyol, an acid numberof 13.8 mg KOH/g (based on as-supplied form), an OH number of 115 mgKOH/g (based on resin solids) and a viscosity of 442 mPa·s at 23° C. Thedispersion contained 2.2% by weight of dipropylene glycol dimethylether, 1.3% by weight of N,N-dimethylethanolamine and about 55.5% byweight of water. The product can be diluted further with water and issuitable for use in aqueous two-component polyurethane coatingmaterials.

Example 5, Comparative

Preparation of a Water-dilutable Polyesterpolyol V

Polyesterpolyol prepared in analogy to example 2 and 3, wheretrimellitic anhydride and ε-caprolactam have been replaced byisophthalic acid, trishydroxyethyl isocyanurate by trimethylolpropaneand benzoic acid by 2-ethylhexanoic acid.

In analogy to example 2 a water-dilutable polyesterpolyol or an aqueouspolyester is prepared from the following components:

1272 g of 2-ethylhexanoic acid, 957 g of hexahydrophthalic anhydride,2184 g of trimethylolpropane, 1032 g of isophthalic acid, 288 g oftrimellitic anhydride, 215 g of N-methylpyrrolidone and 133 g ofN,N-dimethylethanolamine. The resulting product was adjusted with waterto a solids content of 44% by weight. This gave an opaque dispersionwith a bluish shimmer which had a solids content of 43.2% by weight interms of polyesterpolyol, an acid number of 14.3 mg KOH/g (based onas-supplied form), an OH number of 139 mg KOH/g (based on resin solids)and a viscosity of 93 mPa·s at 23° C. The dispersion contained 2.2% byweight of N-methylpyrrolidone, 1.8% by weight ofN,N-dimethylethanolamine and 52.8% by weight of water. The product canbe diluted further with water and is suitable for use in aqueoustwo-component polyurethane coating materials.

Application Examples

In the following application examples conventional methods of coatingstechnology were used to prepare pigmented two-component polyurethanepaints for different fields of use and these paints were applied tometal test panels under standard conditions and cured. In addition tothe specific paint properties for the individual applications, such assolvent and chemical resistance, film hardness and flexibility, forexample, the principal parameters assessed were the drying rate of thepaints, the levelling and gloss of the films, and the water resistance.

Products Employed:

Surfynol ® 104 E: Defoaming wetting agent, air products, sold by W.Biesterfeld&Co., Hamburg, DE Tronox ® R-KB-4: Titanium dioxide pigment,Kerr McGee Pigments GmbH&Co. KG, DE Acrysol ® RM 8: 20% strength inethanol, thickener, Rohm&Haas Deutschland GmbH, Frankfurt/Main, DE Byk ®346 Levelling additive/substrate wetting, Byk Chemie, Wesel, DE Byk ®380 Levelling additive/anticrater agent, Byk Chemie, Wesel, DEBayhydur ® VP Hydrophilicized aliphatic polyisocyanate, Bayer AG LS 2319Leverkusen, DE Surfynol ® 104 BC: Defoaming wetting agent, air products,sold by W. Biesterfeld&Co., Hamburg, DE Baysilone ® VP 10% strength inbutylglycol, slip additive, Borchers Al 3468 GmbH, Monheim, DEBorchigen ® SN 95 Wetting agent and dispersant, Borchers GmbH, Monheim,DE Borchigel ® PW 25 Thickener, Borchers GmbH, Monheim, DE

Example 6

White two-component topcoat material for general industrial coating,based on the polyesterpolyol of example 1.

Component 1

In a commercially customary dissolver (15 minutes at a peripheral speedof 10 m/s) a millbase was prepared to the following formulation:

-   33.00 parts by weight polyesterpolyol I-   0.81 part by weight Surfynol® 104 E-   30.12 parts by weight titanium dioxide Tronox® R-KB-4-   3.13 parts by weight deionized water

The millbase was dispersed in a Skandex shaker with Siliquartz beads of2 mm in diameter for about 60 minutes. The millbase was then separatedfrom the glass beads by sieving. With stirring, the following paintcomponents were added (make-up):

-   12.20 parts by weight polyesterpolyol I (from example 1)-   0.55 part by weight Acrysol® RM 8, 20% strength in ethanol,-   0.21 part by weight Byk® 346-   0.32 part by weight Byk® 380

Thereafter component 1 (formulated polyol component) is ready forfurther use. To produce a two-component paint component 1 was mixed withthe polyisocyanate curing agent (component 2). Component 2 contains thefollowing ingredients:

Component 2

-   15.73 parts by weight Bayhydur® VP LS 2319-   3.93 parts by weight methoxypropyl acetate-   100.00 parts by weight

Components 1 and 2 were mixed at a stirrer speed of 2000 rpm for 2minutes. The finished two-component paint was then adjusted to a sprayviscosity of about 30 s (efflux time from DIN 4 mm cup at 23° C.). Thewhite paint thus formulated was applied using a commercially customaryspray gun (Sata Jet B, nozzle 1.4 mm, pressure 3.5 to 4 bar) to metaltest panels [steel: 20×10 cm, aluminium: 15×7 cm, zinc: 16.5×6.5 cm andUnibond WH/60/OC (iron-phosphated steel): 20×10 cm] and subjected topaint testing after 1 day, 7 days and 14 days of drying at roomtemperature (23° C., 50% relative atmospheric humidity).

Using a doctor blade (120 μm slot width) the paint was applied to glassplates and, with drying at room temperature, the initial drying,evaporation time and gloss were measured. The potlife (defined as thelength of time after which a doubling in spray viscosity occurs) wasdetermined by measuring the efflux time (DIN 4 mm cup at 23° C.). Theinitial drying was determined in accordance with DIN 53 150. Thefollowing technical paint properties were tested on the cured coatings:

Glass plates/ Determination of gloss (20°/60°) in accordance with steel:DIN 67 530 Glass plates: Determination of evaporation time in accordancewith DIN 53 157 Steel/alumi- Testing of adhesion in accordance with ENISO 2409 nium/zinc panel: Steel panel: Testing of Erichsen cupping inaccordance with DIN ISO 1520 Steel panel: Testing of chemical resistance(acetone/xylene, 1 min/5 min exposure) Unibond WH/ Testing of waterresistance after 16 hours of drying at 60/OC: room temperature. Gloss:in accordance with DIN 67 530 Blistering: in accordance with DIN 53 209Adhesion: in accordance with EN ISO 2409

Example 7

White two-component topcoat material for large-vehicle finishing, basedon the polyesterpolyol I.

Component 1

In a commercially customary dissolver (15 minutes at a peripheral speedof 10 m/s) a millbase was prepared to the following formulation:

-   38.91 parts by weight polyesterpolyol I-   1.09 parts by weight Surfynol® 104 BC-   0.91 part by weight Baysilone® VP A13468, 10% strength in    butylglycol-   6.98 parts by weight Borchigen® SN 95-   0.13 part by weight Borchigel® PW 25)-   29.02 parts by weight titanium dioxide Tronox® R-KB-4

The millbase was dispersed in a Skandex shaker with Siliquartz beads of2 mm in diameter for about 60 minutes. The millbase was then separatedfrom the glass beads by sieving. Thereafter component 1 (formulatedpolyol component) is ready for further use. To produce a two-componentpaint component 1 was mixed with the polyisocyanate curing agent(component 2). Component 2 contained the following ingredients:

Component 2

-   15.53 parts by weight Bayhydur® VP LS 2319-   3.88 parts by weight methoxybutyl acetate-   100.00 parts by weight

Components 1 and 2 are mixed at a stirrer speed of 2000 rpm for 2minutes. The finished two-component paint was then adjusted to a sprayviscosity of about 25 s (efflux time from DIN 4 mm cup at 23° C.) withdeionized water. The white paint thus formulated was applied using acommercially customary spray gun of the type Sata Jet HVLP NR 2000 (1.3mm nozzle, pressure 3.5 to 4 bar) from Sata Farbspritztechnik GmbH,Kornwestheim, DE to coated circularly perforated metal panels,dimensions: 150×300 mm, available commercially under Article No.17542H11ME from Heinz Zanders, Liebigstraβe 22, 42719 Solingen, Del.Curing was carried out at 60° C. for 30 minutes and then at roomtemperature.

Examples 8 and 9

As in example 6, white two-component topcoat materials for generalindustrial coating were prepared on the basis of polyesterpolyols II(example 2) and III (example 3) and applied.

Examples 10 and 11

As in example 7, white two-component topcoat materials for large-vehiclefinishing were prepared on the basis of polyesterpolyols II (example 2)and III (example 3) and applied.

Comparative Example 12

As in example 6, white two-component topcoat materials for generalindustrial coating were prepared on the basis of polyesterpolyol IV andapplied.

Comparative Example 13

As in example 7, white two-component topcoat materials for large-vehiclefinishing were prepared on the basis of polyesterpolyol V and applied.

Test Results of Aqueous Two-component Polyurethane Paints Based on thePolyesterpolyols I to IV (General Industrial Coating):

TABLE 1 Results of the technical paint tests Paint from Example No. 6 89 12 Potlife, h 5 6 6 6 Drying, T1/T3 in h 1/5 1.5/5.5 1/5 1.5/5.5Pendulum damping, s after  1 d 90 87 98 110  7 d 96 92 104 115 14 d 9896 107 118 Erichsen extension, mm after 14 d 8.2 8.5 8.3 7.4 Gloss20°/60° 89/96 90/96 90/97 89/96 Resistance¹⁾ to xylene/acetone  1 d 2/22/2 1/2 2/2 5 min exposure time  7 d 1/2 1/2 1/2 1/2 14 d 0/2 0/1 0/11/2 Resistance²⁾ to water after  1 d 80/92 81/93 83/94 70/93  7 d 65/8969/90 72/91 11/28 14 d 46/74 57/78 61/82 — Adhesion¹⁾ to steel after  1d 2 2 2 2  7 d 1 1 1 2 14 d 1 1 1 1 Adhesion¹⁾ to zinc after  1 d 2 2 21  7 d 2 1 1 2 14 d 2 1 1 1 Adhesion¹⁾ to Al after  1 d 2 2 2 2  7 d 2 22 2 14 d 2 2 2 2 Adhesion¹⁾ to Unibond after  1 d 1 1 1 2  7 d 1 1 1 514 d 2 1 1 — ¹⁾0 = best score (nothing found), 5 = worst score (filmcompletely dissolved and/or no longer adhering) ²⁾Water storage test:Determination of gloss after days; the higher the score the better thewater resistanceTest Results of Aqueous Two-component Polyurethane Paints Based on thePolyesterpolyols I to III and V (Large-vehicle Finishing):

TABLE 2 Results of the technical paint tests Paint from Example No. 7 1011 13 Potlife, h 6 6 6 6 Drying, T1/T3 in h 1.5/6 2.5/7 2/6.5 3/8Pendulum damping, s after  1 d 102 82 91 71  4 d 155 121 130 93  7 d 159123 134 96 Erichsen extension, mm after 14 d 9.6 10 10 10 Gloss 20° 9695 95 87 Haze 20 23 24 28 Resistance¹⁾ to xylene  1 d 1 1 1 2 5 minexposure time after  4 d 0 1 0 2  7 d 0 0 0 1 Resistance¹⁾ to MPA  1 d 11 1 2 5 min exposure time after  4 d 0 1 0 2  7 d 0 0 0 1 Resistance¹⁾to premium-grade  1 d 1 1 1 2 petrol  4 d 0 0 0 2 5 min exposure timeafter  7 d 0 0 0 0 Resistance¹⁾ to water  1 d 1 2 1 3 1 h exposure timeafter  4 d 1 1 1 3  7 d 1 1 1 2 ¹⁾0 = best score (nothing found), 5 =worst score (film completely dissolved and/or no longer adhering)Storage Stability of the Polyester Dispersions I to V

The polyester dispersions I to V were stored in a commercially customaryheating cabinet at 40° C. and inspected daily for visible changes (e.g.formation of two phases or of a sediment). At intervals of 7 days boththe viscosity and the acid number of the dispersions was measured. Thecomparative dispersion IV showed an incipient sediment after 94 days andafter 97 days formed two phases, comprising serum and complete sediment;in the case of comparative dispersion V this occurred after 112 and 117days. The dispersions comprising the polyesterpolyols of the inventionstill have no sediment after 157 days. The comparative dispersions IVand V exhibited a sharp drop in viscosity within 94 or 112 daysrespectively and a distinct rise in acid number from 13.8 to 17.4 mgKOH/g and from 16.7 to 20.8 mg KOH/g respectively. In contrast, theviscosity drop and rise in the acid number of the dispersions comprisingthe polyesterpolyols of the invention within 157 days were significantlyless.

-   polyester dispersion I: increase from 16.9 to 18.8 mg KOH/g-   polyester dispersion II: increase from 18.3 to 20.2 mg KOH/g-   polyester dispersion III: increase from 19.1 to 21.2 mg KOH/g    Discussion of the Test Results:

With the polyesterpolyols of examples 1 to 5 it is possible incombination with water-dilutable aliphatic polyisocyanates to prepareaqueous two-component polyurethane paints which possess a sufficientlylong processing time, dry rapidly on application to a substrate, andgive glossy to highly glossy paint films. The paints based on thepolyesterpolyols I to III of the invention all have more rapid drying,greater hardness, higher gloss and better solvent resistance than thepaints based on the comparative polyesters IV and V. Of criticalsignificance, however, is the substantially better water resistance ofthe paint films based on the polyesterpolyols of the invention incomparison to the paints based on the comparative polyesters, and alsothe much better storage stability of dispersions I to III, comprisingthe polyesterpolyols of the invention, in comparison to the polyesterdispersions IV and V.

1. A polyester polyol which contains structural units comprisingstructural unit a) and either or both of structural units b) and c)wherein a) represents a structural unit of general formula (I)

wherein R¹, R² and R³ are identical or different and one or more of thefollowing structural units:

b) represents a structural unit of general formula (II)

and c) represents a structural unit of general formula (Ill)


2. A polyester polyol which contains structural units comprisingstructural unit a) and, as end groups, structural units d) and e)wherein a) represents a structural unit of general formula (I)

wherein R¹, R² and R³ are identical or different and represent one ormore of the following structural units

d) represents a structural unit of general formula (IV)

and e) represents a structural unit of general formula (V)

wherein R⁴ and R⁵ are identical or different and i) represent hydrogen,halogen, C₁–C₁₈ alkyl, C₂–C₁₈ alkenyl, C₂–C₁₈ alkynyl, C₃–C₁₂heterocycloalkyl, C₆–C₂₄ aryl, C₆–C₂₄ heteroaryl, C₁–C₁₈ alkoxy, C₁–C₁₈alkylthio or C₁–C₁₈ alkylamino radicals or ii) with the joining carbonatom of the C₄N five-membered ring form a C₃–C₁₂ cycloalkyl or C₂–C₁₃heterocycloalkyl radical which optionally contains oxygen, nitrogenand/or sulphur or iii) both together with the joining carbon atoms ofthe C₄N five-membered ring form a fused cyclic or polycyclic ring systemwhich is saturated, unsaturated, or partly or fully aromatic, andoptionally contains oxygen, nitrogen and/or sulphur.
 3. The polyesterpolyol according to claim 1 or 2, characterized in that the polyesterpolyol contains free hydroxyl groups and carboxyl groups.
 4. Thepolyester polyol according to claim 1 or 2, characterized in that thehydroxyl number is from 10 to 400 mg KOH/g.
 5. The polyester polyolaccording to claim 1 or 2, characterized in that the acid number is from5 to 100 mg KOH/g.
 6. A process for preparing the polyester polyolaccording to claim 1 by (I) reacting an anhydride of trimellitic acidand/or of pyromellitic acid with a cyclic lactam (B), and (II)synthesizing a hydroxy-functional polyester by adding trishydroxyethylisocyanurate (D1) and optionally adding an alcohol component (C)comprising C1) one or more aliphatic or cycloaliphatic C₃–C₁₀ polyolshaving a functionality of more than 2, C2) one or more aliphatic orcycloaliphatic C₂–C₁₈ diols or C3) one or more aliphatic, cycloaliphaticor araliphatic monofunctional C₁–C₁₈ alcohols, and optionally adding anacid component (A) comprising A1) one or more difunctional carboxylicacids or their anhydrides, A2) one or more polyfunctional carboxylicacids or their anhydrides or A3) one or more mono carboxylic acids, andoptionally adding an isocyanurate-containing isocyanate component (D2).7. A process for preparing the polyester polyol according to claim 2comprising the steps of (I) reacting an anhydride of a difunctionalcarboxylic acid (Al) with a cyclic lactam (B), and (II) synthesizing ahydroxy-functional polyester by adding trishydroxyethyl isocyanurate(D1) and optionally adding an alcohol component (C) comprising C1) oneor more aliphatic or cycloaliphatic C₃–C₁₀ polyols having afunctionality of more than 2, C2) one or more aliphatic orcycloaliphatic C₂–C₁₈ diols or C3) one or more aliphatic, cycloaliphaticor araliphatic monofunctional C₁–C₁₈ alcohols, and optionally adding anacid component (A) comprising A1) one or more difunctional carboxylicacids or their anhydrides, A2) one or more polyfunctional carboxylicacids or their anhydrides or A3) one or more mono carboxylic acids, andoptionally adding an isocyanurate-containing isocyanate component (D2).8. A process according to claims 6 or 7, characterized in that in athird stage, the hydroxy-functional polyester from stage (II) is reactedwith a carboxylic anhydride selected from the group of the difunctionalcarboxylic acids (A1) and/or trifunctional carboxylic acids (A2′), withring opening and half-ester formation.
 9. A solution or dispersioncomprising the polyester polyol according to claim 1 or
 2. 10. A coatingcomposition comprising the polyester polyol according to claim 1 or 2.11. The coating composition according to claim 10, characterized in thatthey are water-containing.
 12. The coating composition according toclaim 10, characterized in that they are solvent-containing.
 13. Thecoating composition according to claim 10, which comprises one or moreoptionally blocked polyisocyanates and also optionally further bindersand optionally auxiliaries and additives.
 14. A substrate coated withthe coating composition according to claim
 10. 15. An adhesivecomposition comprising the polyester polyol according to claim 1 or 2.